1. Field of the Invention
The present invention relates to a reading and writing head with a magnetoresistant element. The invention essentially applies to so-called horizontal, thin-film heads. Such a head is shown in FIG. 1.
2. Discussion of the Background
FIG. 1 shows in section a horizontal head having an e.g. silicon semiconductor substrate 10, in which has been etched a recess 12. Within the latter a lower magnetic layer 14 has been electrolytically formed and has been extended by two vertical pads 16.sub.1, 16.sub.2, which are surrounded by a coil 18, which is embedded in an insulating layer 20. The magnetic circuit is completed by an upper pole piece subdivided into two portions 22.sub.1, 22.sub.2 by an amagnetic spacer 24. An e.g. Fe-Ni magnetoresistant element MR is placed beneath the amagnetic spacer 24. This element is obtained by photoetching using the spacer as the mask. It is therefore self-aligned with respect to the spacer. The head moves in front of a magnetic support 30 where the information to be read or written is recorded.
Such a head is described in French patent application 89 04060 filed by the Applicant on Mar. 29, 1989 and entitled "Magnetic head with magnetoresistance for longitudinal recording and process for the production of such a head".
The device functions as follows. On writing, the current flowing in the coil 18 creates a magnetic field and consequently an induction in the magnetic circuit. The field lines which open out around the spacer induce a magnetization in the support 30.
On reading, a magnetic information recorded in the support 30 produces a magnetic reading field and consequently an induction in the magnetic circuit. This induction in part re-closes across the magnetoresistant element MR. Thus, there is a reading magnetization in the said element, which will lead to a variation of the resistance of the element.